Objective: To analyze the changing oral health status and subsequent dental service utilization of 27,000 nursing home residents provided on-site dental services by Apple Tree Dental 1986-2004, applying repeated measures methodology. Background: Individuals admitted to nursing homes today tend to be older and more functionally dependent than previously. Furthermore, rates of edentulism continue to decline, a trend that substantially increases the risk for oral disease and treatment needs. Addressing the dental service needs of this underserved population requires a clear picture of how the oral health needs of incoming nursing home residents are changing and resultant changes in patterns of dental service utilization. To date, knowledge of the oral health status of nursing home residents has been derived from cross sectional data and limited longitudinal research. To document the oral health status of this population subgroup, the ATD dataset will be used to meet the following Specific aims: 1)To compare service level oral health needs in successive cohorts of nursing home residents receiving initial dental examination during 1986-2004, 2) To compare utilization patterns over time of dental services (count and cost of diagnostic, preventive, restorative, prosthodontic and oral surgery services) in successive cohorts of residents, 3) To use the multi-level nature of the data to estimate the between- and within-resident associations of resident characteristics with dental care utilization outcomes and 4) the resident-specific and mouth site-specific components of variability of dental care utilization. Methods: 1) Initial dental examination data will be analyzed with regression methods to identify cohort effects, 2) Mean number of services /costs will be used to describe an overall pattern of utilization over time. Generalized estimating equations (GEE) will be applied to determine the significance of age and cohort effects. 3) Time-dependent covariates' effects on dental care utilization will be quantified using GEE. 4) Tooth-level outcomes will be modeled using generalized linear mixed models (GLMM) and Bayesian hierarchical models. Public Health Relevance: The oral health needs of the nursing home population have historically been neglected. Residents are increasingly older, more functionally frail, and have more natural teeth. Quantifying over-time changes in the extent of oral health need and disease predictors within the nursing home population is important for resource allocation and policy development. [unreadable] [unreadable] [unreadable]